Engine Mechanical

Client noticed thumping or banging noise when in sharper turns like when navigating a driveway. Also noticeable but not as pronounced when doing faster turns at speed (merging off a freeway).

Diagnostic Process:

Initially the client took his car back to his tire shop since this problem seemed to occur shortly after having tires replaced. The tire shop could find nothing wrong with the basic suspension and drive train components (eg: ball joints, axles and CV joints, struts, etc) and thus they advising seeing a BMW specialist.

Upon arrival Todd performed the same inspection as the tire shop but when that proved to be fruitless he checked the engine mounts – knowing the pattern failure of engine mount to cylinder block bolts. Sure enough the bolts were broken (engine mount bracket removed in this picture):

BMW N52 engine – broken engine mount bolts

Repair Process:

The repair requires extraction of the bolts and replacing them with new.

N52 engine mount bolts

N52 right side engine mount bracket

Once re-secured the vehicle is test drive to ensure the client’s concern has been resolved. We have NOT seen this escalate into bigger problems yet but we suspect that driving one of these cars with a broken / detached engine mount will eventually cause other problems.

Technical Discussion:

The reason BMW use this fastener (bolt) style is the N52 engine has a magnesium block. A steel fastener, in this application, would cease in the block thus aluminum fasteners are employed. Unfortunately they aren’t as strong as steel and can break. On a positive note we have only seen this problem with the all-wheel-drive (xi) vehicles / we suspect this is due to additional rotational forces from the front axles.

Performed pressure cooling system tests – confirmed coolant leakage down the back of the engine.

Double-checked other cooling system components to make sure this was the correct repair.

NOTE: This is a common / known problem on the first generation (9PA) Cayenne. It only affected the V8 engines. When the problem first came to light the repair was much worse: to replace the coolant pipes required removal of the engine to get the rear cross-over coolant flange/pipe out. This made the repair very costly in labor. Porsche later updated the parts so that the pipes could be replaced with the engine in-chassis. The materials were updated as well – from plastic to aluminum.

Repair Process:

Generally the work is straight forward:

Start with removal of the airbox and air snorkel tubing.

Cayenne V8 intake

Remove intake manifold:

Cayenne V8 intake removed

Remove coolant pipes, note that there is a grouping of three on the top and a lager single pipe underneath.

Cayenne – old plastic coolant pipe under intake

To remove the lower pipe you will have to cut it. This is why, when repairing this the old way, the engine had to be removed – there is no ‘collapsing’ of the pipe so they can fit with the engine in-chassis.

NOTE – we stuff shop rags into the intake ports of the engine to ensure nothing accidentally falls into the engine!

Cayenne V8 with under intake coolant pipes removed.

Here’s a close-up of the back

coolant cross over pipe and hoses – rear of engine

Here was the actually leak – hard to see but if you look at the mirror in the middle of the picture you can see the coolant

Lower pipe leak

Here is the leak in the lower pipe (pipe removed). NOTE this leak / crack in the pipe is much (much!) smaller than they typically are when we do this repair

Lower coolant pipe – crack in plastic

Here’s the new / updated parts. NOTE how the larger pipe is now shorter and Porsche have provided a short rubber hose. This change in design is what allows the repair to be done in-chassis (saving very large amounts of labor).

updated coolant pipes (aluminum)

This is a little closer look at the lower three-piece pipe

updated lower pipe design

Going back together – here’s the pipes installed.

new coolant pipes intalled

close up of collapsible / three-piece lower pipe installed.

Conclusion:

After re-assembly we pressure test the system and get the engine up to temps / ensure there are no other leaks and the repair should out-last the rest of the vehicle. NOTE sometimes this coolant leak can also damage the torque converter seal (!) – this is usually the case when a LOT of coolant has washed down the back of the engine. BUT if the vehicle develops a transmission leak shortly after this ‘event’ that is likely what happened. This leak or defect has given the Cayenne a bit of a bad reputation but we advise to consider it in context: the is a top-end performance SUV that is otherwise a blast to own and drive. We see this repair occasionally but it’s not an epidemic. Let other people think it’s a huge problem and then buy yourself a cool V8 Cayenne for a good price – reduced because of everyone’s fear of this problem!

Upon closer inspection it was clear this was NOT the vehicle’s original pump but it WAS a Porsche-OEM replacement.

Brad, as a Gold-Meister Porsche tech with over 15 years experience had never seen this before.

Boxster water pump shaft sheered-off

The pump’s impeller was NOT ceased. Pump had been seeping from the bearing (see yellowish material on pump).

Conclusion:

Boxster new water pump installed

This story ends well: a new pump and belt and then a good road test demonstrated a successful repair. No other cooling system or engine damage occurred. This success was due to a diligent client that pulled over immediately and called in to the shop to arrange a tow-in. AMAZING to see a problem like this but it goes to show anything can happen.

Removed the filter and found that the oil filter housing had been broken from someone doing an oil change.

Broken oil Filter Housing

Removed all of the remaining pieces of metal that were in the oil filter housing and replaced the broken oil filter housing unit.

Started the car and re-Ran VANOS tests and again found that The VANOS degree angles were not changing.

Removed the VANOS and disassembled and found that there was a piece of metal inside the unit that was causing the exhaust VANOS valve to hang up in its bore and not allow oil pressure to the VANOS gear/Timing actuator causing the angles not to change.

Vanos disassembled

Replaced the VANOS Unit with a rebuilt one and test drove the car and reran the VANOS tests and the car is performing well now.

Conclusion:

The client confessed to doing his own oil change and not being able to remove the oil filter cap. As a result excessive force was used on the filler cap causing the internal metal flange to break. Had he then replaced the oil filter stand before proceeding further the vanos would probably not have been damaged. This is one of those tougher lessons to learn about not ignoring something that is broken. End result was good: the car runs well now. Had more metal circulated through the lubrication system there could have been much more extensive engine damage. Great work Tyler on figuring this one out!

Valves, or their ability to seal compression into a cylinder, usually fail for one of three reasons: They overheat and their sealing surfaces pit – causing poor sealing (this is condition is called a BURNT valve).

We ruled this out because burnt valve conditions will cause low compression that will increase during a wet-cylinder test.

Knowing the client was looking for the possibility of an alternate solution we got out the borescope camera to get pictures of the inside of cylinder #6.

The borescope found one of the intake valves stuck open in cylinder #6 – creating a no-compression condition.

We now know: the engine has a possible bent valve or broken valve spring.

We also know: a BENT valve was not very likely because this problem was only in ONE cylinder. Bent valves are caused by out-of-synch timing components and thus almost-always involve more than one.

Removed valve cover

Removed intake camshaft for that cylinder bank and confirmed that the valve was stuck open due to a broken valve spring:

Northstar broken valve spring.

Replaced the valve spring, valve seal and keepers – a job that can be done with the engine in-chassis and without engine disassembly if other tricks are used.

Often dealerships will take the less risky road with repairs. This is common with franchises since they are required to perform their services and their service recommendations within standards agreed upon that allowed them to become a franchised representative of the manufacturer. Our alternate repair required buy-in from the vehicle owner and more risk since the possibility existed that time taken to diagnose and perform this alternate repair could have proven unsuccessful and thus resources would have been wasted. The tipping point came from the use of the bore-scope – a tool that is simple in concept but very powerful. End result: better information lead to a better solution. The client’s out-of-pocket expense was less than 25% of the dealership’s proposed repairs.

Per MINI’s technical service bulletins, removed the valve cover to physically check the valve timing. With the camshaft alignment tools in
place we found that the valve timing was correct.

Also inspected timing chains, guides, and tensioners: all ok.

Further running tests found that the variable Valve timing( VANOS) degree measurements would not deviate from 36degrees.

Monitored the Duty Cycle command to the VANOS Solenoid actuator and noticed that the Duty Cycle was changing when being commanded from the DMEto change but the actual valve timing was not changing.

This lead us to a physical fault with the VANOS system that cannot truly be measure electrically by the DME.
We removed the VANOS Solenoid and found that it was physically broken and was not able to supply engine oil to the VANOS gear and therefore would not change the valve timing. (pictured below – broken solenoid in front / new (good) solenoid behind)

Conclusion:

This is a classic case of a physical inspection trumping what a diagnostic tree / computer diagnostic process suggests. The dealership followed all MINI protocols and formal test procedures to conclude, consistently but incorrectly, that the problem was with the physical valve timing components. Knowing that as a weak-spot in this engine design, MINI’s repair suggestions weren’t a bad thing for the vehicle but would not have fixed the client’s concerns.

In the end, we saved our client over $1300 of misdiagnosed repairs. A big win!

Smart TIP:

This engine is not equipped with a oil level warning system to alert the driver that the engine oil is getting low. We Suggest that every other time you fill your car with gasoline, Check the engine oil.

This failure could have been avoided: the oil pickup tube was clogged from a previous repair. The timing guides were starting to fail and thus were replaced / the shop didn’t sell the additional work of removing the oil pan to clean the pickup tube. As a result pieces from the timing guides made their way to the pickup tube and restricted oil flow. This lead to oil pressure loss and catastrophic failure of the main bearings. Net Result?: Whole engine replacement for this otherwise perfect X5.

Have you seen a six-cylinder BMW (M54 engine) with the low oil pressure light coming on and off? (The RED light in the dash). You may have a bad pressure valve in the oil filter housing causing this condition. Generally BMW’s engines are well-built and this issue isn’t super common but it does happen. The fix is to replace the actual oil filter housing assembly – here’s some pictures of one we did very recently:

Old and New Oil Filter Housing:

Bad Pressure Valve:

Notice how the valve looks ‘off center in the housing? Compare that with the new assembly below:

This isn’t too bad of a job to do – here’s a picture of the engine with the housing removed:

Here’s a disheartening one; from a 1999 BMW 328i. This car had only 160,000 miles on it. Engine failure like this should not happen. BMW’s 6-cylinder engines can last a lot longer than this one did.

The car came in as a rough running / no start condition. After checking basics (fuel pressure, engine codes, etc) we ran a compression test on the engine. It revealed good numbers in the first 3 cylinders and zero (!) compression in the last 3. We got the client’s authorization to diagnose further and we did a leak-down test in those last three cylinders. Next we used a bore scope to view the valves from inside the combustion chamber. We could see that the intake valves were not opening or closing so we suspected a broken camshaft.

We removed the valve cover to look at the valve train and found significant oil sludge. Turning the engine confirmed our fears: The intake camshaft was snapped and the last three cylinders did not have intake valve movement.

This is a classic case of death-by-neglect. This BMW should have had a lot more life in it but due to poor engine oil services the engine sludged, the valve train was compromised for lubrication, and the camshaft snapped. Unfortunately this engine is not worth fixing. To fix it correctly would require complete dis assembly of the entire engine to clean all of the sludge. Net result: this car is probably heading to a junk-yard. What a shame.

This one has actually been documented by BMW in service bulletin # SI B22 01 10

As you can see by the pictures the engine mount bolts on the passenger-side of the engine break. This is because the bolts are aluminum / aluminum bolts are necessary on this engine because the engine block is made out of magnesium (!). Crazy but true. With this client he noticed a clunk on the passenger side of the car that sounded a lot like a bad CV axle or CV axle joint. Not the case. Here’s the pictures: